Development of a microwave sample preparation method for the determination of arsenic in humus and moss samples by graphite furnace atomic absorption spectrometry.

Abstract

Two sample decomposition methods were optimized for the determination of arsenic by graphite furnace atomic absorption spectrometry (GFAAS) in moss and humus samples. In the first method, 5,0 ml of HNO 3 and 3,0 ml of H 2 O 2 were used for the decomposition of 500 mg of sample. When humus samples were decomposed in this way a slight, undissolved residue remained. Therefore, another sample decomposition method, including hydrofluoric acid, was also tested (5,0 ml HNO 3 ; 3,0 ml H 2 O 2 ; 0,4 ml HF; 2,5 ml H 3 BO 3 ). Pyrolytically coated graphite tubes, equipped with integrated or L'vov platfoms, were used in the determination of arsenic by GFAAS. Palladium-magnesium nitrate was used as a matrix modifier. Several reference materials (e.g. humus, moss, lichen, sea lettuce) were analyzed.